This invention relates to an improvement of a plate type condenser of the type wherein heated medium is condensed by a medium to be heated.
In an electric power generating plant wherein an operating medium such as steam is circulated through a steam turbine or a chemical plant for refining substances a condenser is generally used. Condensers used in such plants ordinary comprise a group of circular tubes having smooth inner surfaces and arranged in a horizontal or vertical direction. In some cases, the tubes are provided with fins on their periphery to improve the rate of heat exchange.
Improvement in the efficiency of such a condenser has been difficult for the following reasons:
1. Where the tubes are arranged horizontally, since the heated medium flows sinuously for the purpose of improving the efficiency of heat exchange between the heated medium and the medium to be heated, the pressure loss is large. Moreover, due to poor heat conductivity and rate of heat transfer only about one half of the tubes contribute to heat transfer.
2. Where the tubes are arranged vertically the thickness of the condensed medium increases toward the lower ends of the tubes thus decreasing heat transfer.
3. In addition, as it is necessary to drill a plurality of openings through header plates, a large number of steps for machining and assembling the condenser are required.
4. Where a plurality of tubes are vertically assembled with a small spacing therebetween, the heated medium condenses at a relatively high speed and efficiency at the upper portion of the heat transfer surface, but this is accompanied by a large pressure drop. On the other hand, at the lower portion of the heat transfer surface the flow speed of the heated medium is low because a substantial portion thereof has already been condensed at the upper portion. Accordingly, the pressure loss is small but the efficiency of condensation is greatly decreased because the condensate formed at the upper portion flows downwardly.
Accordingly there has been a great demand for an improved condenser that can eliminate the various difficulties described above.